The pioneer species of primary succession in water are:

The correct answer is Option (2) → Phytoplanktons

Option (2) Phytoplanktons — Correct. In primary succession in water, the pioneer species are the small phytoplankton. Over time they are replaced by free-floating plants, rooted plants, sedges and grasses, and finally trees.

Note 1: A similar question was also asked in CUET (UG) 2023 on 09-06-2023 (Slot 3).

Note 2: This question is from the topic “Succession of Plants” in Chapter 14, Ecosystem, of the pre-rationalised NCERT book. This portion is not in the present NCERT book, where the chapter is now Chapter 12, Ecosystem. The extract below is from the pre-rationalised edition.

NCERT Extract (Pre-rationalised edition, Chapter 14, Ecosystem):
Succession of Plants – “… In primary succession in water, the pioneers are the small phytoplanktons, which are replaced with time by rooted-submerged plants, rooted-floating angiosperms followed by free-floating plants, then reedswamp, marsh-meadow, scrub and finally the trees. The climax again would be a forest.”